Cationic antimicrobial peptides are found in most living organisms as components of their non-specific defenses against pathogens. They have been identified in bacteria, fungi, plants, insects, amphibians, crustaceans, fish, birds and mammals including man, and can be expressed constitutively or induced in response to the presence of a microbe. Although the mode of action of cationic peptides is not well understood, these peptides are thought to interact with cell membranes as part of their action against microbes. The linear cationic sequence RGRAK (SEQ ID. No. 1) is a feature of a class of cationic antimicrobial peptides that form an amphipathic beta-sheet conformation that may be selective in targeting bacterial cells over mammalian cells.
The NPXY consensus motif (SEQ ID No. 2) is a sorting signal present within the cytosolic domain of proteins and is important for the sorting of transmembrane proteins to different compartments of the endosomal-lysosomal system. The NPXY motif is a tyrosine-based sorting signal and is recognized by components of protein coats peripherally associated with the cytosolic surface of membranes. Postulated recognition proteins for NPXY signals are clathrin, AP-2 and Dab2.
Amongst a growing number of cell-penetrating peptides that are able to penetrate cell membranes and translocate different cargoes into cells is the prototypical sequence constituting the viral peptide known as TAT (48-60) (GRKKRRQRRRPPQ) (SEQ ID. No. 3), derived from the HIV-1 Tat protein. Whilst the entire Tat protein is 86 amino acids in length and contains a highly basic region required for translocation activity, the Tat (48-60) peptide is a minimally active sequence containing a 9 amino acid stretch of basic residues required for membrane lytic activity. Tat 48-60 has been shown to be useful in translocating DNA across cell membranes, producing an increase in transfection efficiency over control peptides.
Brevibacterium linens has long been recognized as an important dairy microorganism because its application to the surface of a variety of cheeses, such as Limburger, Münster, Brick, Tilster, Appenzeller and Camembert, provides flavour, colour and suppresses growth of other bacteria (e.g., see Onraedt et al, 2005). B. linens is an aerobic microorganism with a rod-coccus growth cycle, having a temperature growth optimum of 20° C. to 30° C. It is a halotolerant organism with optimum growth at pH 6.5 to 8.5. The growth of B. linens is thought to be an essential prerequisite for the aroma of smear surface-ripened cheeses.
Transposases are ubiquitous non-secreted, intracellular enzymes that catalyse genetic rearrangement within and between genomes through a series of metal-dependent phosphoryl transfer reactions. Putative DNA transposases may be identified via sequence similarity and/or specific signatures in the encoded transposases.